江西银山火山岩型铜、金多金属矿床成矿特点

江西银山铜、金多金属矿床的矿化紧紧围绕多个中心呈有规律地分布,成矿物质既由岩浆从地壳深部带来,又部分来自基底围岩;成矿作用既受燕山期火山机构控制,也受基底构造控制;矿化具有多个中心复合叠加分带的特点,是一个典型的地洼型多因复成矿床。     

Galactic bulges

We model the evolution of the Galactic bulge and of the bulges of a selected sample of external spiral galaxies, via the multiphase multizone evolution model. We address a few questions concerning the role of the bulges within galactic evolution schemes and the properties of bulge stellar populations. We provide solutions to the problems of chemical abundances and spectral indices, the two main observational constraints to bulge structure.     

Weighing the cusp at the Galactic Centre

As stars close to the galactic centre have short orbital periods it has been possible to trace large fractions of their orbits in the recent years. Previously the data of the orbit of the star S2 have been fitted with Keplerian orbits corresponding to a massive black hole (MBH) with a mass of M_BH = 3–4 × 10⁶M_⊙ implying an insignificant cusp mass. However, it has also been shown that the central black hole resides in a ∼1″ diameter stellar cluster of a priori unknown mass. In a spherical potential which is neither Keplerian nor harmonic, orbits will precess resulting in inclined rosetta shaped trajectories on the sky. In this case, the assumption of non‐Keplerian orbits is a more physical approach. It is also the only approach through which cusp mass information can be obtained via stellar dynamics of the cusp members. This paper presents the first exemplary modelling efforts in this direction. Using positional and radial data of star S2, we find that there could exist an unobserved extended mass component of several 10⁵M_⊙ forming a so‐called ‘cusp’ centered on the black hole position. Considering only the fraction of the cusp mass Mequation/tex2gif-inf-4.gif within the apo‐center of the S2 orbit we find as an upper limit that Mequation/tex2gif-inf-6.gif/(M_BH + Mequation/tex2gif-inf-9.gif) ≤ 0.05. A large extended cusp mass, if present, is unlikely to be composed of sub‐solar mass constituents, but could be explained rather well by a cluster of high M/L stellar remnants, which we find to form a stable configuration. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel device with macrophytes and bio balls as a rehabilitation tool for small eutrophic urban ponds: a mesocosm approximation

During the last century, the human-derived impact on freshwater systems has been severe all around the world. Artificial eutrophication has an outstanding relevance in urban aquatic ecosystems and it is recognized as one of the most common problems associated with water deterioration in urban lakes and ponds. Therefore, more studies regarding the trophic interactions and the potential rehabilitation methods should be encouraged. Our aim is to evaluate at a mesocosm scale, a device composed of native aquatic plants, either submerged (SPD) or floating (FPD), including an extra artificial potential refuge (bio balls rolls) for zooplankton as a rehabilitation tool for urban ponds. As regards the impact of the tested devices on water quality variables, FPD provoked a decrease in TP and pH. In turns, SPD maintained the dissolved oxygen concentrations above those registered in FPD. Transparency was significantly higher in the presence of plants at final time. Differences in phytoplankton morpho-functional group diversity and zooplankton functional feeding groups were registered by the end of the experiment. Zooplankton abundance at the artificial refuges was higher than at the water column; a study of the efficiency of the bio balls rolls as potential active/passive refugees is merited.Considering benefits on water quality variables, we suggest that a device combining floating macrophytes plus the bio ball rolls deserves to be further tested at a greater scale in order to be considered as a water rehabilitation tool, including plant harvest.     

FUZZY ISODATA聚类法在地下水水化学分类中的应用

本文以杜热草场水化学资料为例,运用FUZZY ISODATA聚类方法对地下水水化学类型的划分进行了初步研究,并与传统的舒卡列夫法和基于模糊关系聚类法所得结果进行了对比,说明了本方法的可靠性。文中运用该法对研究区水化学成份划分的五种类型,基本符合本区地下水化学成份形成与分布规律,分类合理,计算简便,特别是对水化学成份差别不大的地区更为适用。     

Asymptotic giant branch variables in Baade's Windows

In this work, a sample of luminous M-type giants in the Baade's Windows towards the inner Galactic bulge is investigated in the near-infrared. The ISOGAL survey at 7 and 15 μm has given information concerning the mass-loss rates of these stars and their variability characteristics have been extracted from the MACHO data base. Most are known to be semi-regular variables (SRVs). Here we discuss how their IJHK _S -region colours depend on period and on the presence or absence of mass loss, using results mainly taken from the DENIS and 2MASS surveys.
In order to compare their colours with solar neighbourhood stars, photometric colours on the DENIS, 2MASS and ESO photometric systems have been synthesized for objects in the spectrophotometric atlas of Lançon & Wood. In addition, they have been used to predict the differences in colour indices when stars with strong molecular bands are observed using different photometric systems.
The SRVs are found to inhabit the upper end of the     , K _S colour–magnitude diagram, lying just below the Miras. High mass-loss rates are associated with high luminosity. The near-infrared colours of the SRVs increase in a general way with period and are the reddest for stars with significant mass loss. The average colours of Mira variables, whose periods start at around 200 d in the bulge, are bluer than those of the semi-regulars at this period, particularly in     , thanks to the association of deep water vapour bands with large amplitude.     

Production of neutrons, neutrinos and gamma-rays by a very fast pulsar in the Galactic Centre region

We consider the possibility that the excess of cosmic rays near ∼10¹⁸ eV, reported by the AGASA and SUGAR groups from the direction of the Galactic Centre, is caused by a young, very fast pulsar in the high-density medium. The pulsar accelerates iron nuclei to energies ∼10²⁰ eV, as postulated by the Galactic models for the origin of the highest-energy cosmic rays. The iron nuclei, about 1 yr after pulsar formation, leave the supernova envelope without energy losses and diffuse through the dense central region of the Galaxy. Some of them collide with the background matter creating neutrons (from disintegration of Fe), neutrinos and gamma-rays (in inelastic collisions). We suggest that neutrons produced at a specific time after the pulsar formation are responsible for the observed excess of cosmic rays at ∼10¹⁸ eV. From normalization of the calculated neutron flux to the one observed in the cosmic ray excess, we predict the neutrino and gamma-ray fluxes. It has been found that the 1 km² neutrino detector of the IceCube type should detect from a few up to several events per year from the Galactic Centre, depending on the parameters of the considered model. Moreover, future systems of Cherenkov telescopes (CANGAROO III, HESS, VERITAS) should be able to observe  1–10 TeV  gamma-rays from the Galactic Centre if the pulsar was created inside a huge molecular cloud about  3–10×10³ yr  ago.